This is very pretty, but after scanning the github readme, watching the video and reading the comments I won't be trying it out, certainly would never even consider rolling out to production because:
1. The project is based on a fork of an older version of a currently active professionally and supported project, yet has no intention of keeping up with the source.
2. The introduction of additional frameworks means an increased attack surface and performance penalty, yet the overview claims improved performance and a more maintainable codebase. The statement is either marketing (a lie) or demonstrating the author's lack of understanding systems as a whole.
3. Ultimately this project makes the UI pretty, but does so in the manner inconsistent with enterprise standards and best practices. While Django PBX may not be as sexy as this project its based on a solid foundation (FreeSwitch) and developed by folks who understand and respect stability and security.
FusionPBX does have an API, while not free or cheap, the best solution to building on Fusion would be to build on its APIs, anything else is kind of like stealing.